Study On Mechanical Properties And Wear Resistance Of 3D Printing PEEK For Artificial Joint Replacement

Polyether-ether-ketone(PEEK)has been successfully applied to many orthopedic medical applications such as cranial repair,cervical disc fusion,and joint replacement due to its excellent physicochemical properties and biocompatibility.The current growing demand in the individualized medical market is placing higher technological demands on the ability to meet individual customization and address issues such as patient-specific medical conditions.Traditional manufacturing technologies have difficulty meeting individualized needs,while 3D printing technology can quickly provide cost-effective customized prostheses.This thesis investigates the physicochemical properties and wear resistance in biological environments of PEEK samples prepared by fused deposition molding technology.In this thesis,four printing angles(XY-0°,XY-30°,XY-45°,and XY-90°)are used to prepare different PEEK samples based on the horizontal printing method(XY plane).A variety of testing and analysis methods are used to reveal the microstructure,crystallinity,wettability,surface roughness,hardness,strength,and other mechanical properties of PEEK samples.At the same time,the pin-on-disc wear test is used to systematically study the wear resistance of PEEK sample parts in the environment of bovine serum lubrication,to effectively regulate the components,and to deeply analyze the effects of albumin and hyaluronic acid on the wear resistance and wear mechanisms of PEEK materials.The details of the study are as follows:(1)The results show that the crystallographic indices of the polymer are(110),(111),(200),and(202),which are basically consistent with the microscopic crystal structure of the PEEK samples prepared by conventional injection molding;however,their highest crystallinity value is 27.76%,which is slightly lower than that of PEEK samples obtained by injection molding(30%-35%).Meanwhile,the Raman spectroscopy results show that the intensity ratio I1146/I1598 between the peak 1146 cm-1 of C-O-C and the peak 1598 cm-1 of benzene ring is less different from that of the injection molded PEEK sample.(2)The mechanical properties of PEEK samples are systematically investigated,the results show that the printing angle has a significant effect on the mechanical properties,with PEEK-XY-0° samples having the best tensile strength(80.57±1.40 MPa)and PEEK-XY-30° samples having the best bending and shear strengths of 149.7±3.01 MPa,56.03±2.91 MPa respectively.Although 3D printed prototypes have defects such as melt gaps and internal porosity,making the mechanical properties of 3D printed PEEK prototypes slightly lower than those of conventional injection molded parts,they can still achieve about 80%of the performance of injection molded parts.Meanwhile,the surface roughness of the fused deposited PEEK samples range from 0.106 to 0.156 ?m,meeting the standard for polymeric orthopedic implants(Ra?0.585 ?m).The wettability results show that the contact angles of the 3D printed samples are all less than 90°,similar to injection molded PEEK,indicating that 3D printed PEEK has good hydrophilicity.(3)The effect of printing angle on the wear resistance of PEEK samples in biological environments is systematically investigated.The results show that the printing angle has a minor impact on the wear resistance of PEEK samples in the bovine calf serum lubricantion.After 2 million cycles,the wear rates of PEEK-XY-0°?PEEK-XY-30°?PEEK-XY-45° pins and discs are 5.933×10-6 mm3·N-1·m-1?5.749×10-6 mm3·N-1·m-1 and 4.574×10-6 mm3·N-1·m-1,which are generally higher than the wear rates at one million cycles,but the wear rates are all lower than 10-6 mm3·N-1·m-1 order of magnitude.To explore the reason,when the motion period reaches one million cycles,the sample surface does not occur obvious breakage and peeling;while when the period reaches 2 million cycles,the weak bonding between the fused filaments makes the 3D printed sample wear surface show serious rupture and delamination phenomenon.(4)The results show that when albumin is added to calf serum,the overall wear rate of the sample is relatively small,decreasing to 2.863×10-6 mm3·N·m-1,which is mainly attributed to the adsorption of albumin molecules,reducing the wear effect on surface.When both hyaluronic acid and albumin are added to bovine calf serum lubricant,the viscosity of the lubricant increases,but the wear results are not statistically different compared to the addition of albumin only.Overall,the wear rate of PEEK samples orients to the bovine calf serum bioenvironment with added albumin and hyaluronic acid is low relative to the wear rate of the bovine calf serum lubricant.This thesis investigates the mechanical and wear resistance properties of fused deposition manufactured PEEK.The results show that PEEK prototypes manufactured by fused deposition manufacturing technology can be of greater value as orthopedic replacement materials in the medical field,which can meet the needs in terms of hardness,roughness,and strength,while possessing good wettability,and wear resistance.